This study delves into the design and optimization of mobile microrobots tailored for tasks requiring sub-micrometer precision, addressing key challenges in the miniaturization and efficiency of microrobotic systems. Each microrobot is composed of a mobile platform, a manipulation unit, and a specialized end effector, collectively enabling them to perform a diverse array of operations on various surfaces. The mobile platforms provide three degrees of freedom (DOF) and can support loads ranging from 10 g to 500 g, with actuation based on the slip-stick principle. A novel configuration of the components offers promising characteristics, notably the low voltage required to drive the actuators, facilitating battery integration. The manipulation unit incorporates actuators that utilize a combination of electric motors and piezoelectric materials. The research explores two distinct mobile platforms that vary in dimensional scale and pulling force, both actuated using piezoelectric materials, providing insights into how different design parameters affect performance. The study focuses on the effects of platform design and piezoelectric material variations on the external voltage required for actuation. The findings contribute to the development of more efficient manipulation units, with a key challenge being the further miniaturization of these units through the optimization of piezoelectric material shapes and properties. This research underscores the potential for enhancing the design of compact and efficient manipulation units, which is critical for the advancement of mobile microrobots in precision applications.